Decision tree algorithm in locally advanced rectal cancer: an example of over-interpretation and misuse of a machine learning approach.

PURPOSE: To analyse the classification performances of a decision tree method applied to predictor variables in survival outcome in patients with locally advanced rectal cancer (LARC). The aim was to offer a critical analysis to better apply tree-based approach in clinical practice and improve its interpretation. MATERIALS AND METHODS: Data concerning patients with histological proven LARC between 2007 and 2014 were reviewed. All patients were treated with trimodality approach with a curative intent. The Kaplan-Meier method was used to estimate overall survival (OS). Decision tree methods were was used to select important variables in outcome prediction. RESULTS: A total of 100 patients were included. The 5-year and 7-year OS rates were 76.4% and 71.3%, respectively. Age, co-morbidities, tumor size, clinical tumor classification (cT) and clinical nodes classification (cN) were the important predictor variables to the tree's construction. Overall, 13 distinct groups of patients were defined. Patients aged < 65 years with cT3 disease and elderly patients with a tumor size < 5 cm seemed to have highest rates of survival. But the process over-fitted the data, leading to poor algorithm performance. CONCLUSION: We proposed a decision tree algorithm to identify known and new pre-treatment clinical predictors of survival in LARC. Our analysis confirmed that tree-based machine learning method, especially classification trees, can be easily interpreted even by a non-expert in the field, but controlling cross validation errors is mandatory to capture its statistical power. However, it is necessary to carefully analyze the classification error trend to chose the important predictor variables, especially in little data. Machine learning approach should be considered the new unexplored frontier in LARC. Based on big datasets, decision trees represent an opportunity to improve decision-making process in clinical practice.

Primary thyroid angiosarcoma: A systematic review.

Thyroid angiosarcoma (TAS) is rare and represents a very aggressive malignancy. Its rarity is principally linked to two major pitfalls. Firstly, TAS histopathology diagnosis can be difficult; second, the limited clinical experience with this condition can make its management complex. We conducted a detailed systematic review, focusing on the knowledge available regarding TAS etiopathogenesis, treatment options and prognosis. The aim is to present the main TAS characteristics and to summarize the clinical experiences described worldwide, in order to provide a useful clinical tool.

Excess of weight: is it a modifiable predictive and prognostic factor in locally advanced rectal cancer?

OBJECTIVE: To evaluate the relationship between body mass index (BMI) and rates of treatment tolerance and clinical outcomes in patients with locally advanced rectal cancer treated with a multimodality approach. PATIENTS AND METHODS: This study was conducted on 56 patients with histologically proven rectal adenocarcinoma, staged T3-4, and/or node-positive tumor, which underwent intensified radiochemotherapy (RT-CHT) treatment before surgery. We calculated adiposity indices and analyzed their influence on treatment tolerance and clinical outcomes. RESULTS: Distribution of the 56 patients according to BMI was BMI < 25 kg/m2 (n = 19; 33.9%), BMI 25-29 kg/m2 (n = 29; 51.8%) and BMI ≥ 30 kg/m2 (n = 8; 14.3%). BMI had no significant influence on neo-adjuvant treatment-related toxicity. With a median follow-up of 23 months (range 11-47), the 2-year survival was 85.7%. We did not observe any significant difference among the three BMI categories for any of the outcomes. CONCLUSIONS: This study suggested no evident links between overweight and survival in patients with locally advanced rectal carcinoma treated with neo-adjuvant RT-CHT. Overweight patients tolerate treatment as normal-weight patients.

Radiation therapy for oncological emergencies.

AIMS AND BACKGROUND: Radiation therapy holds a fundamental role in oncological emergencies such as superior vena cava syndrome, spinal cord compression and endocranial hypertension. The purpose of our study was, by comparing schedules of treatment, to confirm the efficacy of hypofractionated radiation therapy. METHODS: From January 1994 to December 1998, 43 patients with superior vena cava syndrome, 37 patients with metastatic spinal cord compression and 108 patients with endocranial hypertension secondary to metastasis were treated at our institution. In the group of patients with superior vena cava syndrome, radiotherapy schedules were: 4 Gy x 5 to a total dose of 20 Gy (23 patients) and 3 Gy x 10 to a total dose of 30 Gy (20 patients). In the group of patients with spinal cord compression, radiation schedules were: 3 Gy x 10 to a total dose of 30 Gy (15 patients); 4 Gy x 5 to a total dose of 20 Gy (12 patients); a single fraction of 8 Gy in 10 cases, repeated after 1 week in 7 responder cases to a total dose of 16 Gy. 5 out of 37 patients were underwent to laminectomy plus stabilization of the spine and post-operative radiotherapy. In the group of patients with endocranial hypertension, radiotherapy schedules were: 6 Gy x 2 to a total dose of 12 Gy (53 patients), repeated after 4 weeks in 34 responder patients and 3 Gy x 10 to a total dose of 30 Gy (55 patients). RESULTS: The patients with superior vena cava syndrome, revaluated after 4 weeks at the end of treatment, obtained a partial remission of symptomatology in 73.9% with 20 Gy and in 75% with 30 Gy. The patients with spinal cord compression obtained symptomatic relief in 73.3% with 30 Gy, in 66.6% with 20 Gy and in 70% of cases treated with 8 Gy. The patients with endocranial hypertension obtained symptomatic relief in 64.1% with 12 Gy and in 63.3% with 30 Gy. CONCLUSION: Histology, pretreatment and performance status were important prognostic factors for the response to therapy. Our results demonstrated no significant difference among different schedules of radiotherapy and confirmed the importance of radiotherapy for oncological emergencies: it improves the quality of life and, in responding patients, is associated with a longer survival time.

Current radiotherapic procedures and preservation of salivary function in patients with head and neck cancer.

Head and neck tumours have poor prognosis: with surgery and radiotherapy, local control is achieved but is associated with damage to speech and swallowing function. Conventional 2-D radiotherapy is based on one fraction of 1.8-2.0 Gy per day; increasing the number of fractions, a higher dose can be administered, with an increase in local control. Today, conventional treatment can be replaced by new techniques: with 3-D Conformal Radiotherapy, higher doses of radiation can be delivered to cancer cells while reducing the amount of radiation received by surrounding healthy tissues: Intensity Modulated Radiation Therapy permits an irregular dose distribution that conforms exactly to the volume of the target, increasing local tumour control and survival and decreasing radiation-induced side-effects.